CN1968939A - Process for the production of an olefin oxide, a 1, 2-diol, a 1,2-diol ether, or an alkanolamine - Google Patents

Abstract

A process for the epoxidation of olefins comprising the steps of contacting an olefin- and oxygen-containing feedstock with a catalyst comprising a silver component and a highly selective dopant deposited on a fluoride mineralized support and producing an olefin oxide-containing product mixture wherein the concentration of carbon dioxide in the feed is less than 2 mol% relative to the total feed.

Description

Process for producing olefin oxides, 1,2-diols, 1,2-diol ethers or alkanolamines

technical field

The present invention relates to a process for the production of olefin oxides, 1,2-diols, 1,2-diol ethers or alkanolamines.

Background technique

In olefin epoxidation, a feedstock containing an olefin and a source of oxygen is contacted with a catalyst under epoxidation conditions. The feedstock may contain other components. Alkenes react with oxygen to form olefin oxides. The result is a product mixture containing olefin oxide and generally unreacted starting material and combustion products.

Carbon dioxide is a by-product of the epoxidation process and may be present in the feedstock. Carbon dioxide may be present in the feed as a result of recovery and recycling from the product mixture along with unconverted olefins and/or oxygen. Carbon dioxide may also be provided to the feedstock in other ways.

The catalyst comprises silver deposited on a support, typically an alpha-alumina support, usually with one or more additional elements. Olefin oxides can react with water to form 1,2-diols; with alcohols to form 1,2-diol ethers; or with amines to form alkanolamines. Thus, 1,2-diols, 1,2-diol ethers, and alkanolamines can be produced in a multi-step process that initially involves epoxidation of olefins followed by conversion of the resulting of olefin oxides.

The performance of silver-containing catalysts can be evaluated based on selectivity, activity and operational stability in olefin epoxidation. Selectivity is the mole fraction of olefin converted to give the desired olefin oxide. As the catalyst ages, the olefin fraction reacted typically decreases with time. In order to maintain the desired constant level of olefin oxide production, the reaction temperature will be increased. However, increasing the temperature causes a decrease in the selectivity of the reaction to the desired olefin oxide. In addition, the equipment used in the reactor is usually only resistant to a certain level of temperature. Therefore, the reaction must be terminated when the reaction temperature reaches a temperature unsuitable for the reactor. Therefore, the longer the selectivity can be maintained at a high level and the epoxidation can be carried out at an acceptably low reaction temperature while maintaining an acceptable level of olefin oxide production, the catalyst loading can be maintained in the reactor The longer the amount, the more product is obtained. Stability refers to how the selectivity and/or activity of the process changes over the course of using the catalyst loading, ie as more olefin oxide is produced.

Modern silver-based catalysts may include, in addition to silver, one or more highly selective dopants, such as components containing rhenium, tungsten, chromium or molybdenum. High selectivity catalysts are disclosed in eg US-A-4761394 and US-A-4766105. US-A-4766105 and US-A-4761394 disclose that in silver-containing catalysts rhenium can be used as a further component with the effect that the initial peak selectivity of olefin epoxidation is increased.

Depending on the catalyst used and the parameters of the olefin epoxidation process, the time required to reach initial peak selectivity, ie the highest selectivity achieved in the initial stages of the process, may vary. The initial peak selectivity of the process may be reached, for example, after only 1 or 2 days of operation, or may be reached, for example, after as much as 1 month of operation. The working examples given in these US patents show a tendency towards higher selectivity at higher rhenium contents up to 3 mmol rhenium/kg catalyst on a support with a surface area of 0.42 m ² /g. EP-A-352850 also teaches that a recently developed catalyst comprising silver on an alumina support and promoted with alkali metal and rhenium components has very high selectivity.

Although these improvements have been achieved, it is still desirable to further improve the performance of epoxidation catalysts containing silver and highly selective dopants in order to specifically increase the initial peak selectivity of the process and the stability of the achieved selectivity.

Contents of the invention

The present invention provides a process for the epoxidation of olefins comprising the steps of contacting an olefin- and oxygen-containing feedstock with a catalyst comprising a silver component deposited on a fluoride mineralized support and highly selectively doped agent; and producing an olefin oxide-containing product mixture wherein the concentration of carbon dioxide in the feedstock is less than 2 mol%.

The present invention also provides a process for the production of 1,2-diols, 1,2-glycol ethers or alkanolamines, the process comprising converting an olefin oxide into a 1,2-diol, 1,2-glycol ether or alkanolamines, wherein olefin oxides are obtained by the olefin epoxidation process of the present invention comprising reacting olefins with oxygen.

Detailed ways

The present invention provides a process for the epoxidation of olefins in which an olefin is contacted with oxygen in the presence of a supported catalyst under epoxidation conditions to form an olefin oxide.

When the olefin epoxidation process is carried out using a catalyst containing a silver component deposited on a fluoride mineralized support and a highly selective dopant and where the concentration of carbon dioxide in the feedstock is below 2 mol%, the process shows high Initial peak selectivity. In addition, the method shows improved stability.

By incorporating fluorine into the support, a fluoride mineralized support is obtained. For the purposes of the present invention, a fluoride mineralized support is obtained by combining alpha-alumina or a precursor of alpha-alumina with a fluorine-containing substance, and calcining the combination, which, when calcined, contains Fluorine substances release fluoride, typically hydrogen fluoride. The combination can be formed into shaped bodies, for example by extrusion or spraying, before calcination. Preferably, calcination is carried out at less than 1200°C, more preferably less than 1100°C. Preferably, calcination is performed at a temperature above 900°C, more preferably above 1000°C. If the temperature exceeds 1200° C. significantly, the amount of fluoride released may be too high and the morphology of the carrier may be adversely affected.

The manner in which the fluorine-containing substance is introduced into the carrier is not limited, and those methods known in the art for introducing the fluorine-containing substance into the carrier (and those fluoride-mineralized carriers obtained therefrom) can be used in the present invention . Methods for preparing fluoride mineralized supports are disclosed, for example, in US-A-3950507 and US-A-4379134, which are hereby incorporated by reference.

In some embodiments, the fluoride mineralized carrier may have, and preferably does have, a granular matrix whose morphology may be characterized as either a lamellar or platelet type (the two terms are used interchangeably). Thus, particles having a size greater than 0.1 μm in at least one direction have at least one substantially planar major surface. Such particles may have two or more planar major surfaces. In alternative embodiments of the present invention, supports having the platelet-type structure described and prepared by methods other than the fluoride mineralization methods described herein may be used.

A suitable procedure for incorporating the fluorine-containing species into the support includes adding the fluorine-containing species to alpha-alumina or an alpha-alumina precursor. [alpha]-alumina precursors referred to herein are those materials that can be converted to [alpha]-alumina after calcination. Alpha-alumina precursors include hydrated aluminas, such as boehmite, pseudoboehmite, and gibbsite, and transitional aluminas such as chi, k, gamma, delta, theta, and eta aluminas.

If hydrated alumina is used, the fluorine-containing substance can be suitably added to the hydrated alumina, and the combination can then be formed into a shaped body, for example, by extrusion or spraying. The alumina hydrate is then converted to alpha-alumina by calcining the shaped body. Preferably, calcination is performed at less than 1200°C. During calcination, fluoride is released. Similarly, fluorine-containing species may be suitably added to transitional aluminas such as gamma-alumina or combinations of transitional and hydrated aluminas. The combination is formed into shaped bodies and calcined as previously described.

In another suitable method, fluorine-containing substances can be added to the shaped body of alpha-alumina or alpha-alumina precursors or mixtures thereof. The shaped body is then calcined. In another suitable method, the fluorine-containing species may be added to the support after calcination, ie after formation of alpha-alumina. In this method, the fluorine-containing species may conveniently be incorporated in the same manner as silver and other accelerators, for example by impregnation, typically vacuum impregnation.

As mentioned previously, it is preferred to carry out the calcination at a temperature below 1200°C. However, the invention is independent of the manner in which the calcination is carried out. Therefore, the present invention contemplates various methods of calcination known in the art, such as holding at one temperature for a certain period of time, then raising the temperature to a second temperature for a second period of time.

Fluorine-containing substances can be added by any known method. In one such suitable method, alpha-alumina or an alpha-alumina precursor is treated with a solution containing a fluorine-containing species. The combination is co-milled and converted into shaped bodies. Similarly, the shaped body can be vacuum impregnated with a solution containing a fluorine-containing substance. According to this method, any combination of solvent and fluorine-containing species that results in the presence of fluoride ions in solution can be used.

Fluorine-containing substances that can be used in the present invention are those that release fluoride, typically in the form of hydrogen fluoride, when calcined, preferably at temperatures below 1200° C., after incorporation into a support according to the present invention . It is preferred that the fluorine-containing substance releases fluoride when calcined at a temperature of 900°C to 1200°C. Such fluorine-containing species known in the art may be used in the present invention. Suitable fluorine-containing substances include organic and inorganic substances. Suitable fluorine-containing species include ionic, covalent and polar covalent compounds. Suitable fluorine-containing species include _F2 , aluminum trifluoride, ammonium fluoride, hydrogen fluoride and dichlorodifluoromethane.

Fluorine-containing species are generally used in amounts such that catalysts comprising silver deposited on a fluoride-mineralized support and highly selective dopants when used in olefin epoxidation processes where the carbon dioxide concentration in the feedstock is below 2 mol %, show The selectivity of ® is greater than that of the comparative catalyst deposited on the same non-fluoride mineralized support without layered or platelet-type morphology. Typically, the amount of fluorine-containing species added to the support is at least 0.1 wt%, and not more than 5.0 wt%, expressed as the weight of elemental fluorine used relative to the weight of the support material into which the fluorine-containing species is incorporated calculate. Preferably, the amount of fluorine-containing substances is not less than 0.2 wt%, more preferably not less than 0.25 wt%. Preferably, the amount of fluorine-containing substances is not more than 3.0 wt%, more preferably not more than 2.5 wt%. These amounts refer to the amount of material initially added and do not necessarily reflect the amount that may ultimately be present in the finished vehicle.

Other than the fluoride mineralization described above, there are generally no limitations on the carriers that can be used in the present invention. Typically, a suitable support comprises at least 85 wt% alpha-alumina, more typically 90 wt%, especially 95 wt%, usually up to 99.9 wt%, based on the weight of the support. The support may also include silica, alkali metals such as sodium and/or potassium and/or alkaline earth metals such as calcium and/or magnesium.

There is also no limitation on the surface area, water absorption or other properties of suitable supports. The support may suitably have a surface area relative to the weight of the support of at least 0.1 m ² /g, preferably at least 0.3 m ² /g, more preferably at least 0.5 m ² /g, and in particular at least 0.6 m ² /g; and relative to the weight of the support The weight, surface area of the support may suitably be at most 10 m ² /g, preferably at most 5 m ² /g, and in particular at most 3 m ² /g. "Surface area" as used herein is understood to refer to the surface area determined by the BET (Brunauer, Emmett and Teller) method described in Journal of the American Chemical Society 60 (1938) pp. 309-316. High surface area supports, particularly when they are alpha-alumina supports optionally further comprising silica, alkali metals and/or alkaline earth metals, provide improved performance and operational stability. But when the surface area is very large, the carrier tends to have lower crush strength.

The carrier may suitably have a water absorption of at least 0.2 g/g, preferably at least 0.3 g/g, relative to the weight of the carrier. The water absorption of the carrier may suitably be at most 0.8 g/g, preferably at most 0.7 g/g, relative to the weight of the carrier. Higher water absorption may be advantageous in view of more efficient deposition of silver and other elements (if any) impregnated on the support. But at higher water absorption, the support or the catalyst prepared therefrom may have lower crush strength. As used herein, water absorption is considered to be measured according to ASTM C20 and is expressed as the weight of water that can be absorbed into the pores of the carrier relative to the weight of the carrier.

The catalyst includes silver as a catalytically active component. Significant catalytic activity is typically obtained by using an amount of silver of at least 10 g/kg by elemental weight relative to the catalyst weight. Preferably, the catalyst comprises silver in an amount of 50-500 g/kg, more preferably 100-400 g/kg, eg 105 g/kg or 120 g/kg or 190 g/kg or 250 g/kg or 350 g/kg.

In addition to silver, the catalyst may also include one or more highly selective dopants. Catalysts containing highly selective dopants are known from US-A-4761394 and US-A-4766105, which are hereby incorporated by reference. Highly selective dopants may include, for example, compositions containing one or more of rhenium, molybdenum, chromium, and tungsten. Highly selective dopants may be present in a total amount of 0.01-500 mmol/kg, calculated as elements (eg rhenium, molybdenum, tungsten and/or chromium) based on the total catalyst. Rhenium, molybdenum, chromium or tungsten may suitably be provided as oxides or as oxyanions such as perrhenate, molybdate and tungstate in salt or acid form. High selectivity dopants may be used in the present invention in amounts sufficient to provide catalysts having the high selectivity dopant levels disclosed herein. Particularly preferred catalysts include, in addition to silver, a rhenium component, and more preferably also a rhenium co-promoter. The rhenium co-promoter is selected from tungsten, molybdenum, chromium, sulfur, phosphorus, boron, compounds thereof and mixtures thereof.

When the catalyst comprises a rhenium component, rhenium typically may be present in an amount of at least 0.1 mmol/kg, more typically at least 0.5 mmol/kg, and preferably at least 1.0 mmol/kg, specifically at least 1.5 mmol/kg, relative to Catalyst weights are calculated in terms of elemental amounts. Rhenium is typically present in an amount of up to 5.0 mmol/kg, preferably up to 3.0 mmol/kg, more preferably up to 2.0 mmol/kg, in particular up to 1.5 mmol/kg. Again, the form of rhenium provided to the support is not critical to the invention. For example rhenium may suitably be provided as an oxide or as an oxyanion such as rhenate or perrhenate in salt or acid form.

If present, the preferred amount of rhenium co-promoter is from 0.1 to 30 mmol/kg relative to the weight of the catalyst based on the total amount of the elements concerned, namely tungsten, molybdenum, chromium, sulfur, phosphorus and/or boron. The form in which the rhenium co-promoter is provided to the support is not critical to the invention. For example rhenium co-promoters may suitably be provided as oxides or oxyanions in salt or acid form.

Suitably, the catalyst may also include a Group IA metal component. Group IA metal components typically include one or more of lithium, potassium, rubidium and cesium. Preferably, the Group IA metal component is lithium, potassium and/or cesium. Most preferably, the Group IA metal component comprises cesium or a combination of cesium and lithium. Typically, the Group IA metal component is present in an amount of 0.01-100 mmol/kg, more typically 0.50-50 mmol/kg, more typically 1-20 mmol/kg, calculated as total elemental amount relative to catalyst weight. The form in which the Group IA metal is provided to the support is not critical to the invention. For example Group IA metals may suitably be provided as hydroxides or salts.

As used herein, the amount of the Group IA metal component present in the catalyst is considered to be the amount extractable from the catalyst with deionized water at 100°C. The extraction method consisted of heating the catalyst sample in 20 ml portions of deionized water for 5 minutes at 100°C, extracting 10 g of the catalyst sample 3 times, and measuring the amount of catalyst in the combined extracts by using known methods such as atomic absorption spectrometry. related metals.

Catalyst preparation, which includes the incorporation of silver, highly selective dopants and Group IA metals, can be used to prepare catalysts useful in accordance with the present invention. The method of preparing the catalyst includes impregnating the carrier with a silver compound and reducing to form metallic silver particles. Reference is made, for example, to US-A-5380697, US-A-5739075, EP-A-266015, US-B-6368998, WO-00/15333, WO-00/15334 and WO-00/15335, which are incorporated herein Reference.

The reduction of cationic silver to metallic silver can be achieved during the step in which the catalyst is dried, so that the reduction does not require a separate process step. This may be the case if the impregnation solution includes reducing agents such as oxalates. This is suitably carried out at a reaction temperature of at most 300°C, preferably at most 280°C, more preferably at most 260°C, and suitably at a reaction temperature of at least 200°C, preferably at least 210°C, more preferably at least 220°C The drying step is carried out for a period of at least 1 minute, preferably at least 2 minutes, and suitably for a period of up to 60 minutes, preferably up to 20 minutes, more preferably up to 15 minutes, and more preferably up to 10 minutes.

Although the epoxidation process of the present invention can be carried out in a variety of ways, it is preferred that it is generally carried out in a fixed bed under epoxidation conditions as a gas phase process, ie wherein the feedstock is contacted in the gas phase with the catalyst present as a solid material. Epoxidation conditions are the combination of temperature and pressure conditions under which epoxidation occurs. Generally, the process is carried out as a continuous process such as a typical industrial process involving fixed bed, tubular reactors.

A typical industrial reactor has multiple elongated tubes, usually arranged parallel to each other. Typical tubes used in commercial reactors have a length of 4-15 meters and an internal diameter of 1-7 cm, although the size and number of tubes may vary from one reactor to another. Suitably, the inner diameter is sufficient to accommodate the catalyst. In particular, the inner diameter of the tube is sufficient to accommodate the shaped body of the carrier. In an operation on an industrial scale, the process of the invention will often involve an amount of catalyst of at least 10 kg, such as at least 20 kg, usually in the range of 10 ² -10 ⁷ kg, more often in the range of 10 ³ -10 ⁶ kg.

The olefin used in the epoxidation process of the present invention can be any olefin, for example an aromatic olefin such as styrene or a diene (whether conjugated or not) such as 1,9-decadiene or 1,3-butanediene alkene. Mixtures of olefins can be used. Typically the olefin is a monoolefin such as 2-butene or isobutene. Preferably, the olefin is a mono-alpha olefin such as 1-butene or propylene. The most preferred olefin is ethylene.

The olefin concentration in the feed can be selected within a wide range. Typically, the olefin concentration in the feed is at most 80 mole percent relative to the total feed. Preferably, it ranges from 0.5-70 mol%, specifically 1-60 mol%, based on the same basis. Feedstock as used herein is considered to be the composition in contact with the catalyst.

The epoxidation process of the present invention can be based on air or oxygen, see "Kirk Othmer Encyclopedia of Chemical Technology", 3rd Edition, Volume 9, 1980, pp. 445-447. In air-based processes, air or oxygen-enriched air is used as the oxidant source, while in oxygen-based processes high purity (typically at least 95 mol%) oxygen is used as the oxidant source. Most epoxidation units today are oxygen-based units, which are the preferred embodiment of the present invention.

The oxygen concentration in the feedstock can be selected within a wide range. In practice, however, oxygen is usually used in concentrations that avoid the flammability limit. Typically, the oxygen concentration employed is in the range of 1-15 mol%, more typically 2-12 mol%, of the total feedstock.

To stay above the flammability limit, the oxygen concentration in the feedstock can be reduced as the concentration of olefins increases. The actual safe operating range depends on the reaction conditions, such as reaction temperature and pressure, along with the starting material composition.

Organic halides may be present in the feedstock as reaction modifiers to increase selectivity and inhibit the undesired oxidation of olefins or olefin oxides to carbon dioxide and water relative to the formation of the desired olefin oxides. Acceptable organic halides include organic bromides and organic chlorides, with organic chlorides being more preferred. Preferred organic halides are chlorinated or brominated hydrocarbons and are preferably selected from methyl chloride, ethyl chloride, dichloroethane, dibromoethane, vinyl chloride or mixtures thereof. The most preferred organic halides are ethyl chloride and dichloroethane.

Organic halides are generally effective as reaction modifiers when used in low concentrations within the feedstock, for example up to 0.01 mol % relative to the total feedstock. Specifically when the olefin is ethylene, it is preferred that the organic halide is present in the feedstock in a concentration of at most 50 x 10 ^-4 mol %, specifically at most 20 x 10 ^-4 mol %, more specifically at most 15 x 10 ^-4 mol%, and preferably present in the raw material at a concentration of at least 0.2× ^10-4 mol%, specifically at least 0.5× ^10-4 mol%, more specifically at least 1× ^10-4 mol%, relative to the entire raw material.

In addition to olefins, oxygen and organic halides, the feedstock may contain one or more optional components such as inert gases and saturated hydrocarbons. An inert gas, such as nitrogen or argon, may be present in the feedstock in a concentration of 30-90 mol%, typically 40-80 mol%, relative to the total feedstock. The feedstock may contain saturated hydrocarbons. Suitable saturated hydrocarbons are methane and ethane. If saturated hydrocarbons are present, they may be present in an amount of up to 80 mol%, specifically up to 75 mol%, relative to the total feedstock. They may generally be present in an amount of at least 30 mol%, more often at least 40 mol%. Saturated hydrocarbons may be added to the feedstock in order to increase the flammability limit of oxygen.

The epoxidation process can be carried out using epoxidation conditions including temperatures and pressures selected from a wide range. Preferably, the reaction temperature is in the range of 150-340°C, more preferably in the range of 180-325°C. The reaction temperature can be increased gradually or in multiple steps, for example increasing the reaction temperature in steps of 0.1-20°C, specifically 0.2-10°C, more specifically 0.5-5°C. The total increase in reaction temperature may range from 10-140°C, more typically 20-100°C. The reaction temperature can typically be increased from a level in the range of 150-300°C, more typically 200-280°C when fresh catalyst is used, to a range of 230-340°C, more typically 240-325°C, when the activity of the catalyst decreases due to aging level within.

The epoxidation process is preferably carried out at a reactor inlet pressure in the range of 1000-3500 kPa. "GHSV" or Gas Hourly Space Velocity is the volume of gas at standard temperature and pressure (0° C., 1 atm, ie 101.3 kPa) that passes per unit volume of packed catalyst. Preferably, when the epoxidation process is a gas phase process including a fixed bed catalyst, the GHSV is in the range of 1500-10000 Nl/(l.h).

An advantage of the present invention is that when the process is carried out at low concentrations of carbon dioxide in the feed, the process exhibits high initial peak selectivity and improved stability, wherein said improved stability includes improved selectivity stability and and/or improved activity stability. Therefore, the method of the present invention is preferably carried out under the condition that the carbon dioxide concentration in the raw material is lower than 2 mol%. Preferably the concentration of carbon dioxide is below 1 mol%, even more preferably the concentration of carbon dioxide is below 0.75 mol%. When practicing the invention, the concentration of carbon dioxide is typically at least 0.1 mol%, and more typically the concentration of carbon dioxide is at least 0.3 mol%. The most preferred carbon dioxide concentration is 0.50-0.75 mol%. It is contemplated that the method of the present invention can be performed at a standard concentration of carbon dioxide, that is, the concentration of carbon dioxide is very close to 0 mol% if not 0 mol%. Indeed, methods performed in the absence of carbon dioxide are also within the scope of the invention.

When operating at these carbon dioxide concentrations in the feedstock, the olefin epoxidation process achieves greater than 85% peak selectivity. Preferably, this method achieves an initial peak selectivity greater than 87%. More preferably, this method achieves a peak selectivity greater than 89%, even greater than 90%. Typically this method achieves selectivities of up to 92%.

Additionally, the olefin epoxidation process achieves improved stability when operating at these carbon dioxide concentrations in the feedstock using a catalyst comprising a silver component and a rhenium component deposited on a fluoride mineralized support. Thus, when the process achieves an initial peak selectivity of greater than 90%, it is expected that the process can exhibit a cumulative olefin oxide of 0.4 kilotons of olefin oxide per cubic meter of catalyst used (kT/m ³ ). A selectivity greater than 90%. After a cumulative olefin oxide production of 0.8 kT/m ³ , a process achieving greater than 90% initial peak selectivity can be expected to show greater than 89% selectivity.

The olefin oxide produced can be recovered from the product mixture by using methods known in the art, such as by absorbing the olefin oxide from the product mixture in water and optionally recovering the olefin oxide from the aqueous solution by distillation. The olefin oxide may be converted to 1,2-diol, 1,2-glycol ether or alkanolamine in a subsequent process using at least a portion of the aqueous solution containing the olefin oxide. The method for this transformation is not limited, and those known in the art can be used. The term "product mixture" as used herein is understood to mean the product recovered from the outlet of the epoxidation reactor.

Conversion to 1,2-diols or 1,2-diol ethers may include, for example, reacting the olefin oxide with water, suitably using an acid or base catalyst. For example, in order to mainly prepare 1,2-diol and less 1,2-diol ether, in the liquid phase reaction, in the presence of an acid catalyst such as 0.5-1.0 wt% sulfuric acid based on the entire reaction mixture, at 50- Reaction of olefin oxides with a 10-fold molar excess of water at 70°C at 1 bar absolute pressure, or in gas phase reactions at 130-240°C and 20-40 bar absolute pressure, preferably in the absence of catalyst . If the proportion of water decreases, the proportion of 1,2-glycol ether increases. The 1,2-diol ethers thus produced may be diethers, triethers, tetraethers or subsequently higher ethers. Alternatively, 1,2-glycol ethers can be prepared by converting an olefin oxide with an alcohol, in particular a primary alcohol such as methanol or ethanol, by substituting an alcohol for at least a portion of the water.

Conversion to alkanolamines may involve reacting an olefin oxide with an amine such as ammonia, an alkylamine, or a dialkylamine. Anhydrous or aqueous ammonia can be used. Anhydrous ammonia is typically used to facilitate the production of monoalkanolamines. Reference is made, for example, to US-A-4845296, which is hereby incorporated by reference, for methods which may be used for the conversion of olefin oxides to alkanolamines.

1,2-diols and 1,2-diol ethers can be used in various industrial applications such as food, beverage, tobacco, cosmetics, thermoplastic polymers, curable resin systems, detergents, heat transfer systems, etc. Alkanolamines can be used, for example, in the treatment of natural gas ("sweetening").

Organic compounds such as alkenes, 1,2-diols, 1,2-diol ethers, alkanolamines, and organic halides referred to herein typically have up to 40 carbon atoms, and more typically Up to 20 carbon atoms, specifically up to 10 carbon atoms, more specifically up to 6 carbon atoms. As defined herein, ranges for the number of carbon atoms (ie, carbon numbers) include the numbers specified at the upper and lower limits of the range.

Having generally described this invention, a further understanding can now be obtained by reference to the following examples, which are provided for purposes of illustration only and are not intended to be limiting unless otherwise indicated.

Example 1 - Preparation of a carrier for fluoride mineralization

An impregnation solution was prepared by dissolving 12.24 g of ammonium fluoride in 300 g of distilled water. The content of ammonium fluoride is determined by the following formula:

where F is a factor of at least 1.5. The water content was determined by the following formula:

F×m _alumina ×WABS

where m _alumina is the mass of transition γ-alumina starting material, wt% NH ₄ F is the weight percent of ammonium fluoride used, and WABS is the water absorption of transition alumina (g H ₂ O/g alumina ). The factor "F" is large enough to provide an excess of impregnation solution to completely submerge the alumina.

Extruded transition alumina cut into individual cylindrical shaped bodies is used. 150 g of transitional alumina was evacuated to 20 mmHg over 1 minute and the final impregnating solution was added to the transitional alumina under vacuum. Release the vacuum and allow the transition alumina to come into contact with the liquid for 3 min. The impregnated transition alumina was then centrifuged at 500 rpm for 2 minutes to remove excess liquid. The impregnated transitional alumina pellets were dried at 120°C for 16 hours under flowing nitrogen.

The dry impregnated transition alumina is placed in a first high temperature alumina crucible. About 50 g of calcium oxide was placed in a second high temperature alumina crucible. The high temperature alumina crucible containing impregnated transition alumina is placed in the second high temperature alumina crucible containing calcium oxide, and then covered with a third high temperature alumina crucible smaller in diameter than the second crucible so that the third crucible and The calcium oxide blocks the impregnated transitional alumina. Place this assembly in a cooling furnace. The furnace temperature was increased from room temperature to 800°C over a period of 30 minutes. The assembly was then held at 800°C for 30 minutes before being heated to 1200°C over a period of 1 hour. The assembly was then kept at 1200° C. for 1 hour. The furnace is then allowed to cool, and the alumina is removed from the assembly.

The carrier thus obtained (carrier A) had the properties described in Table 1. This support has a granular matrix whose morphology can be characterized as a lamellar or platelet type.

Table 1

Carrier performance Carrier A Performance water absorption (g/g) surface area (m ² /g) 0.590.71

The preparation of embodiment 2-catalyst

This example describes the preparation of the raw silver impregnation solution used to impregnate the support material described in the following examples.

In a 5 liter stainless steel beaker, dissolve 415 g of reagent grade sodium hydroxide in 2340 ml of deionized water. Adjust the temperature of the solution to 50 °C. In a 4 liter stainless steel beaker, 1699 g of silver nitrate was dissolved in 2100 ml of deionized water. Adjust the temperature of the solution to 50 °C. Under stirring, while maintaining the temperature at 50°C, the sodium hydroxide solution was slowly added to the silver nitrate solution. The resulting slurry was stirred for 15 minutes. The pH of the solution was maintained above 10 by adding NaOH solution as needed. A washing procedure was used which consisted of removing liquid by use of a filter rod followed by replacement of the removed liquid with an equal volume of deionized water. This washing procedure was repeated until the conductivity of the filtrate dropped below 90 microohm/cm. After the last wash cycle was completed, 1500 ml of deionized water was added, followed by 630 g of oxalic acid dihydrate (4.997 mol) in 100 g increments under stirring while maintaining the solution at 40°C (±5°C). The pH of the solution was monitored during the addition of the last 130 g of oxalic acid dihydrate in order to ensure that the pH did not drop below 7.8 over an extended period of time. Water was removed from the solution with a filter rod, and the slurry was cooled to below 30°C. 732 g of 92% ethylenediamine were slowly added to the solution. During this addition, the temperature was maintained below 30°C. The mixture was stirred manually using a spatula until enough liquid was present to mechanically stir. The final solution was used as the raw silver impregnation solution for the preparation of the catalyst.

By mixing 95.2 g of a silver stock solution having a specific gravity of 1.546 g/cc with a solution of 0.0617 g ammonium perrhenate in ~2 g 1:1 ethylenediamine/water, 0.0287 g ammonium perrhenate dissolved in ~2 g 1:1 ammonia/water g ammonium metatungstate and 0.1268 g lithium nitrate dissolved in water to prepare the impregnating solution for the preparation of Catalyst A. Additional water was added to adjust the specific gravity of the solution to 1.507 g/cc. Mix the doping solution with 0.136 g of a 44.62% cesium hydroxide solution. Catalyst A was prepared using this final impregnation solution. 30 g of support A was evacuated to 20 mmHg over 1 minute and the final impregnation solution was added to support A under vacuum, then the vacuum was released and the support was allowed to contact the liquid for 3 minutes. The impregnated carrier A was then centrifuged at 500 rpm for 2 minutes to remove excess liquid. The impregnated support A pellets were placed in a vibrating shaker and dried in flowing air at 250°C for 5.5 minutes. The final composition of Catalyst A was 18.3% Ag, 400 ppm Cs/g catalyst, 1.5 μmol Re/g catalyst, 0.75 μmol W/g catalyst and 12 μmol Li/g catalyst.

Example 3 - Catalyst Test

Catalyst A is used to produce olefin oxides from ethylene and oxygen. For this, 3.9 g of pulverized catalyst were loaded into a stainless steel U-tube. The tube is immersed in a molten metal bath (heating medium) and the ends are connected to a gas flow system. The catalyst weight used and the inlet gas flow were adjusted to give a gas hourly space velocity of 3300 Nl/(l.h), calculated relative to the uncomminuted catalyst. The flow rate of the regulating gas is 16.9Nl/h. The inlet gas pressure is 1370kPa.

A gas mixture of 30%v ethylene, 8%v oxygen, 0.5%v carbon dioxide, 61.5%v nitrogen and 2.0-6.0 parts per million volume (ppmv) of ethyl chloride.

For Catalyst A, the initial reactor temperature was 180°C, said temperature would be ramped to 225°C at a rate of 10°C per hour, and then adjusted to achieve the desired constant level of ethylene oxide production, conveniently at reactor The partial pressure of ethylene oxide at the outlet or the mole percent of ethylene oxide in the product mixture is measured.

At an ethylene oxide production level of 41 kPa ethylene oxide partial pressure, Catalyst A provided an initial peak selectivity of greater than 87%, actually greater than 89%, and as high as 91%. At the same ethylene oxide production level, comparative catalysts prepared on non-fluoride mineralized supports without layered or platelet-type morphology are expected to provide lower initial peak selectivities.

When Catalyst A has achieved a cumulative ethylene oxide production of 0.4 kT/ ^m3 , Catalyst A provides a selectivity greater than 87%, actually greater than 89%, and as high as 91%. The comparative catalyst prepared on a non-fluoride mineralized support without lamellar or platelet type morphology is expected to provide lower selectivity at the same ethylene oxide production level.

When Catalyst A has achieved a cumulative ethylene oxide production of 0.8 kT/ ^m3 , Catalyst A provides a selectivity greater than 86%, actually greater than 88%, and as high as 90%. The comparative catalyst prepared on a non-fluoride mineralized support without lamellar or platelet type morphology is expected to provide lower selectivity at the same ethylene oxide production level.

Claims (10)

1. olefin epoxidation process, this method comprises the steps:

The raw material that contains alkene and oxygen is contacted with catalyzer, and described catalyzer comprises silver components and the highly selective doping agent on the carrier that is deposited on fluoride-mineralization, and described highly selective doping agent comprises one or more in rhenium, molybdenum, chromium and the tungsten; With

Generation contains the product mixtures of alkene oxide, and wherein concentration of carbon dioxide is lower than 2mol% with respect to total raw material in the raw material.

2. the process of claim 1 wherein that concentration of carbon dioxide is lower than 1mol% with respect to total raw material in the raw material, be specially and be lower than 0.75mol%.

3. claim 1 or 2 method, wherein concentration of carbon dioxide is 0.50-0.75mol% with respect to total raw material in the raw material.

4. each method of claim 1-3, wherein said highly selective doping agent comprises rhenium, and described catalyzer also comprises the rhenium co-promoter that is selected from tungsten, molybdenum, chromium, sulphur, phosphorus, boron, its compound and composition thereof one or more.

5. each method of claim 1-4, wherein said catalyzer also comprises IA family metal.

6. each method of claim 1-5, wherein said carrier comprises Alpha-alumina.

7. each method of claim 1-6, wherein said alkene comprises ethene.

8. olefin epoxidation process, this method comprises the steps:

The raw material that contains alkene and oxygen is contacted with catalyzer, described catalyzer comprises and is deposited on silver components and the highly selective doping agent that has on the carrier of particulate substrates that form is stratiform or platelet-type that described highly selective doping agent comprises one or more in rhenium, molybdenum, chromium and the tungsten; With

Generation contains the product mixtures of alkene oxide, and wherein concentration of carbon dioxide is lower than 2mol% with respect to total raw material in the raw material.

9. it is the planar major surfaces substantially that the method for claim 8, the form of wherein said stratiform or platelet-type make at least one direction size have at least one greater than the particle of 0.1 μ m.

10. produce 1,2-glycol, 1, the method for 2-glycol ethers or alkanolamine for one kind, this method comprises makes alkene oxide change into 1,2-glycol, 1,2-glycol ethers or alkanolamine, wherein said alkene oxide obtains by each epoxidizing method of claim 1-9.